memory_get_usage 疑问
求助 memory_get_usage 疑问
echo memory_get_usage();
for($ii=0; $ii
$c[] = array('A'=>12);
}
echo("\n");
echo memory_get_usage();
?>
输出结果
---------- run php ----------
58088
294872
输出完成 (耗时 0 秒) - 正常终止
为啥在没有任何变量的时候,上面已存在占用内存。谢谢
------解决方案--------------------
$c[] = array('A'=>12);
$c 不是变量吗?
------解决方案--------------------
是的,你的程序不也要使用内存吗?
------解决方案--------------------
php进程启动,也是需要emalloc内存的。
------解决方案--------------------
不必太纠结这些数值是否精确,本来这些数值也就是个参考...
------解决方案--------------------
关于php的内存管理,我推荐你去看一下Laruence的播客:
http://www.laruence.com/2011/03/04/1894.html
相信看完后你就明白了。
php对内存的管理,不是像你相像的那样单纯,没任何操作前不会有任何内存占用,而实际上,你载入的扩展,以及php本身预定义的全局符号表等等都会占用内存。另外,php不是像c语言的malloc那样,你定义个变量,就一定会去找os要,unset时就立刻释放。一个字节不差的返回给你。尤其对于使用数组时申请内存和释放内存时会产生更奇怪的问题。
在c语言中,我们要定义一个不确定元素个数的数组时,都是先malloc一个预估的大小,当数组变大超出我们预申请的大小时,再重新malloc。在php中这一切都帮你做好了,中间过程是隐含的,所以当你用memory_get_usage查看时会发现和你想的不一样。

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